Controlling the dynamics of quantum mechanical systems sustaining dipole-forbidden transitions via optical nanoantennas

Abstract

We suggest to excite dipole-forbidden transitions in quantum mechanical systems by using appropriately designed optical nanoantennas. The antennas are tailored such that their near field contains sufficiently strong contributions of higher-order multipole moments. The strengths of these moments exceed their free-space analogs by several orders of magnitude. The impact of such excitation enhancement is exemplarily investigated by studying the dynamics of a three-level system. It decays upon excitation by an electric quadrupole transition via two electric dipole transitions. Since one dipole transition is assumed to be radiative, the enhancement of this emission serves as a figure of merit. Such self-consistent treatment of excitation, emission, and internal dynamics as developed in this contribution is the key to predict any observable quantity. The suggested scheme may represent a blueprint for future experiments and will find many obvious spectroscopic and sensing applications.

A generalized Kerker condition for highly directive nanoantennas

“…The redshift of the spectral position of highest directivity can be explained by the difference between near-and farfield illumination [41]. The calculated emission rate enhancement, usually termed Purcell factor F , is calculated by the enhancement of the emitted power to the far-field compared to its emission without nanoantenna, F = P rad na /P rad fs [42]. The antenna efficiency η is calculated as the fraction of emitted power not dissipated by the nanoring to the total power emitted by the dipole [ Fig.…”

Self-assembled plasmonic metamaterials

“…It is beyond the scope of this contribution to review all of them, but it remains to be mentioned that applications such as optical rulers [ 216 ], sensors [ 217 ], plasmonic substrates for surface enhanced Raman scattering [ 218 ], novel tools for spectroscopy that are sensitive to probe electric quadrupolar or magnetic dipolar transitions [ 136 ], solar cells [ 219 ], high density optical storage devices [ 220 ], or light emitting diodes [ 221 ] were all shown to profit from the incorporation of plasmonic NPs. We anticipate an exciting time in the near-future where eventually some of these applications are not only explored in academia but may find their way into real-world products.…”

Plasmonic nanoring fabrication tuned to pitch: Efficient, deterministic, and large scale realization of ultra-small gaps for next generation plasmonic devices

“…On the one hand, a gapsize down to 15 nm will allow the realization of strong coupling effects like energy splitting or level crossing if the rings are arranged as dimers 7 or in higher order superstructures. 2 On the other hand, the enhanced light-matter-interaction inside gaps and the provided homogeneous field distribution inside the nanorings promise new insights and applications when combined with quantum systems to form hybrid plasmonic quantum systems.…”

“…The enormous impact of plasmonic structures on the dynamics of close-by quantum systems has been demonstrated in groundbreaking experiments 1 and new effects have been predicted. 2 Especially, the use of plasmonic structures functionalized by spectrally tunable quantum dots offers new applications in photovoltaics, 3 nonclassical light generation, 4 and unprecedented sensing devices. 5 However, to turn ideas into devices either scientifically or from an application perspective, it is of paramount importance to provide high-throughput reproducible fabrication processes for the plasmonic nanostructures of interest.…”